Mark V






Repair the VRF Preselector into the Yaesu FT1000 MarkV & Field models by IC8POF

(Click on any of the images in this repair to view them full size) Link to IC8POF Web Site


Problem: My rig is now 3 years old in jan.2005. One day pressing the VRF ON\OFF key the received signals sounded not more so clear and loud. The intensity of the signals was going up and down without any QSB ... What was happening?

At once the brain run in a sort of flowchart list for a possible cable break from the antenna down to the rig, but all the cabling were and are OK.
What and where the received signal could be interrupted in such a "strange" way was not clear at that moment. So I switched the rig OFF waited some seconds and re-ON, pressed again the VRF knob and all seemed ok. OK go to listen again on the band for a possible QSO. Had some contacts around and all seemed ok. Then I played again the VRF switch to ON, all was OK. Back to OFF and the signals disappeared with an up\down intensity. Again the received signals were going up and down, but not due to a QSB. At this time I was realizing that something inside the rig had gone wrong .

Remembering of the old days when a faulty contact could be cured by tapping on the case, specially the TV and Radio sets with lot of tubes, I gently went to tap on the rig's chassis with the fingers, but nothing happened . All the front switches had been turned and pushed, but nothing happened other than each own predefined function . Then I pressed the MOX button ( the VRF was OFF with almost all the received signal attenuated) just for curiosity and because I guessed that the TX knobs had nothing to do with a faulty RX_signal_chain. At once the rx-signal came out again in its original strength.... That was strange, but so it was. And I recalled that in a TRX rig there are many circuits in common or switched IN&OUT from RX to TX and vice versa. Every time I switched the VRF_Off the rx-signals disappeared and when I pressed the MOX the signals were back again.
The rx-signal attenuation with the VRF_Off disappeared every time the rig was turned back from TX to RX. That is why I have never noticed that fault before.

Solution: Having discovered the fault was not all. It had to be ensured which component caused the problem. Studying the electric schematic was a first step. Tracing the received signal on the paper is quite simple. Untill the rx-signals reach the preselector there are no active components, only relays. Therefore I supposed that it should be a faulty relay (Rel1005) . It is the relay that switches the rx-signal into the VRF chain . BUT :
How to ensure myself that was a faulty relay the cause of such incorrect reception?
EASY : open the rig , access to the RF_board, switch it ON and tap with a pen
on the board and the relays and see (better listen) what it happens.

Easy to say but harder to do. Because the part to check is well packed inside the FT1000mk_V_Field rig. Follow this link for a step_by_step How_To access into the rig explanation , for you will be easier than for me the first time. Having the rig opened and secured that it can be switched ON without any error , you can try to "tap" around on the relays with a pencil. IMPORTANT : tap very gently on the relays. I discovered almost soon that if the tap had been strong then also some other relay could move its anker not only the one suspected to be faulty. Repeat more times the tapping over the suspect relay to be sure that it is the faulty one. Now you must decide only when to replace the relay. Follow the "Access into the Rig" procedure and change it. 


VRF Block Diagram



Tools needed :
A screwdriver, a small soldering iron (8/15 watt) or a regulated one, a desoldering pump, a magnifier glasses and of course a couple of those famous TX2 relays as this one in the photo





But where could be purchased such Nais Matsushita TX2-12V relays ? Most furnished electronic shops list this item.
I found it at a well known supplier in EU_lands: Conrad Electronics at Its part number is : Artikel-Nr.: 504788-14 SIGNALrelays TX 2U 2A 12V at 4,76 EUR for 1 piece. (still same price on feb2006) and for the magnifier glasses I have chosen a head magnifier with interchangeable lenses as this one: KOPFBANDLUPE + SCHEINWERFER, VERSTELLBAR Artikel-Nr.: 812379-14 Preis 35,95 EUR

Third : how to remove such mini relays ?
Well, once the faulty item is found it is not so much difficult to get it out of its place on the board.


taking the relay out

testing for the new one

showing the new soldering


testing on the board


The 3 photos above show the few steps needed to do the change. Sucking the tin from the relay pads is easy. Should be used a vacuum sucker care must be taken to the board pads. The copper pads are not as strong as one may imagine.

The following picture shows how looks like the VRF circuitry on the RF board.
RF board
Reclosing the rig : be careful to route all the wires and cables away from the possible pinching of the screws.
Enjoy using your re-vitalized rig and use as less as possible the VRF tuning and bypass relays.




Notes on the Yaesu FT1000 mkV & Field preselector.

I own this fine rig since 5 years. The only complaint I have about it is the VRF feature. First because it is not as effective as the publicity promised and my expectations were, second because the relays used in the VRF unit are fragile compared to its product specs and third because to replace a defective relay is not an easy exercise. That is a big handicap for such an equipment. Specially when this failure happens hundred of times around the world as the FT1000MP reflector and my email correspondence show.

  • Therefore my advice is :

    • do not use the VRF :-> ,

    • or use it at minimum possible ,

    • turn the VRF tuning knob SLOWLY ...not like a F1 steering gear!

    • be prepared to repair the radio .

But I still consider the MkV series a very good rig. Even if my 15 years old FT1000 listens to every signal the MkV does . The future will show if the new FT 2000 & 9000 models will have a REALLY better VRF in construction and functionality of the MP MkV series . Comments and improvements will be appreciated. 73 de Phil IC8POF



This site was last updated 08/27/07